Fuel system for heaters



Sfep 4s 1953 E. J. BODENSIECK 25679343 FUEL SYSTEM FOR HEATERS Filed Dec. 6, 194e 22 35 @553 42 ZQ, 4.-' -VEP l JUSTUS BODENSECK Patented Sept. 4, 1951y v FUEL SYSTEM Fon HEATERs Ernst Justus Bodensieck, Euclid, Ohio, assignor to Thompson Products, Inc., Cleveland, Ohio,

a, corporation of Ohio Application December 6, 1946, serial No. 714,605

This invention relates to a system for maintaining a constant ratio of two propelled fluids in spite of variations in speed of the fluid-propelling means.

Specically, this invention relates to a heater assembly especially adapted for motor vehicles such as buses and the like.

While the invention will hereinafter be specifically described as embodied in a bus heater system, it should be understood that the principles of this invention are generally applicable for the automatic control of fluid flow to maintain aconstant ratio or proportion of two different iiuids in spite of the fact that variations in speed of the means for propelling the fluids would normally change the ratio or proportion.

In bus heater systems, it is conventional to drive a fuel pump and an air blower from a single electric motor that is energized by current from a generator driven by the internal combustion engine which drives the bus. The voltage of this current varies considerably since the bus motor, in normal operation, will drive the generator at widely different speeds. Voltage changes will vary the speed of the electric motor, thereby changing the speed of the pump and the blower. Air ow from the blower varies as the rst power of the speed of the motor driving the blower. However, heretofore variation in the speed of the pump has not appreciably changed the rate of flow of the fuel pumped thereby because relief valves have kept a constant pressure on the discharge side of the pump irrespective of speed and the combustion chamber of the heater'would receive a relatively constant supply of fuel with a widely varying supply of air. As a result, slowing down of the motor speed frequently produced smoking conditions in the combustion chamber due to inadequate supply of air forV thorough combustion. Conversely, speeding up ofthe motor produced a lean fuel conditionA in the combustion chamber.

A further deficiency in the known bus heater units existed due to the inability to'stop dribbling of fuel into the combustion chamber of the unit during periods of rest. During such times fuel on the discharge side of the pump would drain into the combustion chamber, forming a pool therein which, of course, is highly undesirable for efficient operation.

The present invention not only eliminates the variations in the fuel-air ratio heretofore caused by variations in driving speeds for the air blower and fuel pump, but also eliminates'the heretofore-encountered dribbling of'fuel into the combustion chamber during periods of rest.

The invention now makes possible the use of a motor speed regulator to vary the rate of heat generation of a heater unit in 'accordance with ambient .temperature conditions. 1

60. motor. I3 also drives a gear pump I8 receiving a through a fan belt connection I2.

4 Claims. (Cl. 237-12.1)

`In accordance with the invention, a by-pass around the positive displacement pump is provided with a restricted orifice and the nozzle in the combustion chamber is equipped with a spring-biased shut-off Valve that will stop fluid ow as soon as the pump is stopped. The bypass with the restricted orice maintains fuel in" the discharge liney at the desired pressure during operation of the pump at normal speed. At lower speeds of the pump this pressure drops and decreases fluid flow to the nozzle in the exact proportion to match the decreased air flow caused by the reduced motor speed. The orifice thus.

operates to maintain a constant fuel-air ratio over a wide range of varying motor speeds.

,An object of the invention is to maintain a. constant air-fuel ratio in a heater system for a bus or the like in spite of variations in speeds of operation of the means driving the fuel pump and air blower.

Another object of the invention is to provide a system for maintaining a constant ratio of propelled uids irrespective of variations in speeds of operation of the devices propelling the fluids.

A still further object of the invention is to provide a control system for supplying different fluids in a vdesired ratio even when different means propel the fluids and have different vflow rates when driven at different speeds.

Another object of the invention is to provide a fuel system for a heater or the like wherein a predetermined pressure must be established before fuel can be sprayed, and wherein the possibility of spraying fuel for very short periods of time insuiiicient to establish combustion is eliminated.

Other and further objects of the invention will b' e apparent to those skilled in the art from the following detailed descriptions of the annexed sheet of drawings which, by way of a preferred example only, illustrate one embodiment ofthe invention.

" On the drawings:

Figure 1 is a diagrammatic view illustrating a bus heater system.

Figure 2 is a somewhat diagrammatic view of a portion of the apparatus shown in Figure 1 and illustrating some parts in vertical cross section.

Figure 3 is a view of a shut off valve also shown in Figure 2 but illustrating the valve in opened position.

As shown on the drawings:

As shown in Figure 1, an internal combustion engine I0 drives a generator II as is customary An electric motor I3 is energized from the generator II through wires I 4 and drives an air blower I5 which discharges through a duct I6 into the combustion chamber I1 of a heater assembly. The

fuel, such as kerosene or the like, from a supply tank |9 through an inlet pipe 20. The pressured fuel from thepump I3 flows through a discharge pipe 2| into ai valve unit 22 having a spray nozzle 23 depending therefrom. The valve unit and spray nozzle are arranged so that the spray will; discharge into the combustion chamber I1. A by-pass pipe line 24 connects the inlet pipei 2l) and the discharge pipe 2| aroundl the pump. i8. This by-pass 2l| has a housing 25 incorporated therein receiving a screw plug 26 having an integral rod or pin portion 26a thereon, vas best shown in Figure 2. A sleeve 21 is press-fitted inthe housing and receives the pin 26a therethrough Yto1 cooperate therewith for defining a restricted flow passageway l2&3 in the'bynpass.z As shown-in. Figure Y2, theplug 26 can be removed from Ythe housing and replaced with ar plug having a pin of--a` diierent sizel thereby changing the capacity ofthe restriction 28.Y

Waterfrom-a tank 29, shown in Figure 1is` supplied-to a coil Si? in thecombustion chamben |`|-torbe heated therein and fed to a radiator 3|; Affanf32blows airthrough the radiator foi-.being heatedwith the hot water to heat the occupied areafofthebus. Water from the-radiator 3|'. isreturned through pipe line 33. to l.the tank` 29.

A spark plugfl projects into the'cornloustionA chamber |'!\and maybe energized in Aa Couven-- tional manner to produce aspark in the'combus-I tion Vchamber to ignite the fuel sprayed-therein throughthe nozzle 2S.' Air from the ductA l5 furnishes*suiiici'ent oxygen'for` the combustion. Thespentproducts o1 combustion are-.removed from the combustion chamber through the ex-lV haust-pipe 35.y

Asbest-shown in VFigure 2, the valve unit 22finc-ludes ahousing with vaY-bore Bfopening through onesend thereof at an internally threaded portion 35a; andopening through theother end thereof at a reduced-'diameter pcrtioniib to providea shoulder Stic intermediate the ends. A sleeve3'l is inserted in thebore Vand is bottomed 'against the shoulder 36e. The discharge'tube 2| from the pump |8 is secured inthe reduced-diameter portionb ofthe bore and :supplies thevfuel'to thepassageway 38 through the v sleeve 3'?. A plunger 33 is slidable inthe bore 3bV and has a conica-liface 39a adapted to project into `the passageway and to Yengage the end of the `sleeve 31 for sealing the passageway. The plunger has a groovefb intermediate its endsreceivinga rubbei-seal ring Q therein to prevent leakage along theplunger. A lug 39e is provided on the end oi" the"plunger remote from-the conical face '39av thereof. A" coil spring Gil is?` bottomed on theplunger around the lug 35e and is compressed-byl a closure plug il threaded intothe lportionf36a of thebore: 'A gasket'42 interposed between the end of the housing and the headof the plug pre-Y vents'leakage out ofthe bore 36.-

Afpassageway i3 communicates with theA borer 39 adjacent the sleeve 3l and connects fthebore 39with the interior of the nozzle unit 23.V This nozzle unit 23 Vincludes a" head 24 withan'orificeY 44a in the end thereof. An insert member 45'- has a pointed end 45a projectinginto the orifice 44o: andcoacting therewith to atomize fluid.

As illustrated in Figure 3, when the plunger 39" is forced away `from the-sleeve 3l, the fullv force.- of? iiuid pressure in the passageway 38 of the sleeve`v acts onthe full face 39a of the plunger; When the pointed'portion of the face 39aseats onl thersleevevSrI, only fa small area of the fa'ceislex-V posed-.to the pressure in the passagewaySSS;and.v

therefore as soon as the pressure in the passageway 38 builds up suiciently to crack the face 39a off of the sleeve-31, theentireffacearea is exposed to this pressure and the plunger 39 is immediately retracted beyond the passageway 43. Asa result, a very fast-acting valve action is obtained, andthe valve only opens to a fully opened position. Therefore, the nozzle 23 either receives full ow frorntheY passageway 38, or no flow at all.

The restricted. passageway 28 provided between the pin 26aV andthe sleeve 21 in the by-pass 24 joins'thedischarge pipe 2| with the intake pipe 28 .andas soon as the pump |8 is stopped the valve 22 is immediately closed by the spring 49 and thus is only subject tointake'pressure. As a resuit, the`V valve Y need not seal against residual pump pressuresqimthe.discharge line after the pump has stopped.

The restrictedpassageway 28 'provides a fixed oricerso that the-pressure in the discharge pipe 2| will be maintained in directproportion vto the speedof operation ofthepump. Therefore, when thev pumpslows down,.the pressure in the discharge=line2| will bedecreased, and vice versa. The oricezsize isselected to maintain a predeterminedipressurein thefdischarge pipe 2| when the pump isoperated atynormal speed. Under this predetermined pressure, the nozzle will spray fuel into ther combustionchamber l'! in the correct burning proportionsT relative to the air in'Av constant pressure on the. discharge side ofv the pump irrespectivecof the'motor speed, thereby maintaining a'substantia'lly constant fuel feed irrespective of 'variations in air ow. As a result,

combustion chanibersfofv the structures heretofore provided Werevfrequently flooded with fuel as well.as-frequentlysupplied with too lean a fuel mixture.

Theyalver 22.*only opens when sufficient pressure ha`s-been^developedinthe'discharge pipe 2|, and'then-opens'fullyto supply the nozzle without interference.

valverfully 'closes'fand ino dribbling -of fuel occurs through the-nozz1ei Since the fixed oriiice-l arrangement is pro'-l vided,` heretofore-encountered difliculties with movable relieffvalves; suchas improper seating ofthe valveduetoxdirt on the valve seat, and theV If desired, a motor speedregulator., such" asa rheostat-R; 0rthelike, can be included inthe leadY wirefto. thel motor-:fl 3*;.toselect the speed level ofthemotor for deliberatevariation of therateof a-ir and fuelgow tovary theheat generation The regulator-R, if'

ofv the .combustion Yunit- |1. desired, canY be automatically' set by aV thermal unit T- undertheinuence of ambient temperature conditions; This arrangement will varythe heat Vrelease of the .system in accordance with thev requirements of thafspaceibeingfheated, andisf When the discharge pressure;r falls beneath a predetermined minimum, the

preferable to the usual intermittent operation of a bus or automobile heater. The speed control arrangement is made possible because the system of this invention maintains an air-fuel ratio suitable for eicient operation over a wide range of flow rates,

The above descriptions will show wherein the invention provides a shut-off valve and restricted orifice arrangement for a fluid flow system to maintain a fixed ratio of propelled fluid even though the speeds of the propelling means for these fluids change and vary their action on the fluid.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. A vehicle heating system comprising a'variable speed electric motor, an engine driven generator adapted to be carried by the vehicle to energize said motor at variable output voltages, a fuel pump, an air blower, said electric motor forming a common driving means for said fuel pump and said air blower, means to supply wholly liquid fuel to the input side of said fuel pump, a combustion chamber, duct means to supply fuel discharged by said fuel pump to said combustion chamber, inlet means for said combustion chamber to receive air from said air blower, a springbiased shut-off valve in control of said duct means to seal off the fuel discharged by said pump upon stoppage of the pump, a by-pass connecting the intake anddischarge sides of the pump, and a fixed orifice defining means in said by-pass to maintain a constant air-fuel ratio in said combustion chamber as the speed of said electric motor varies during the open period of said valve, said orifice defining means relieving pressure on said valve when said pump is stopped so that said valve will rapidly close and need seal against inlet pressure only.

2. In combination with a motor adapted to be operated at variable speeds by an engine-driven generator means adapted to be carried on a. vehicle, a liquid pump driven by the motor, means to provide wholly liquid fuel to said pump, a bypass around the pump, a spray nozzle, a normally 'closed spring-biased valve controlling flow of said fuel from the pump into the nozzle, and a constantly open fixed `orifice dening means in said by-pass to maintain a pump discharge pressure proportionate with the speed of the motor driving the pump when said valve is open, said by-pass relieving pressure on the valve as soon as the pump is stopped for prompt closing of the valve to avoid dribbling of liquid through the nozzle.

3. In combination with an engine-driven vehicle heater system having a combustion chamber fed by a blower and a positive displacement fuel pump both driven by a common motor energized by an engine-driven generator means adapted to be carried by the vehicle, a fuel pump by-pass line between the discharge and suction sides of said pump, a fixed orifice in said by-pass line, means to provide wholly liquid fuel to said pump, and burner means to receive fuel from said pump for burning in the combustion chamber, said burner means including a spring-biased valve to seal olf the fuel discharged by said pump upon stoppage of the pump, said orifice operable to maintain the air-fuel ratio at the burner means constant when said valve is open and to relieve discharge pressure of said pump upon stoppage of said pump, thereby precluding drip and dribble through said burner means.

4. A heater for engine-driven vehicles comprising a power generator adapted to be driven at variable speedsxby the vehicle engine, a motor driven by the generator at speeds responsive to the variable output of the generator, a blower driven by the motor, a pump driven by the motor,

a combustion chamber having inlet means to receive air from the blower, a fuel tank supplying wholly liquid fuel to the pump, a nozzle for spraying said fuel into the combustion chamber, a spring-biased valve between said nozzle and said pump, a by-pass around the pump, a fixed restriction in said by-pass, means for igniting fuel in the combustion chamber, means for circulating heat transfer fluid through the combustion chamber to be heated therein, and a radiator heated by said heat transfer fluid, said fixed restriction and said by-pass together constituting a fixed orice and being constructed and arranged to maintain a desired fuel pressure at the nozzle when said valve is open and during operation of said electric motor at varying speeds in response to variations of outputI of said generator and to release the fuel pressure at said valve upon stopping said motor, whereby compensation against the decrease in air flow from said blower to said combustion chamber is effected and dribble from said nozzle is precluded.

ERNST JUSTUS BODENSIECK.

REFERENCES CITED The following references are of record in the flle of this patent:

UNITED STATES PATENTS Number Name Date 587,613 Schlager Aug. 3, 1897 1,652,026 Loifer Dec. 6, 1927 1,817,051 Williams Aug. 4, 1931 2,000,733 Avery May 7, 1935 2,006,865 Lake July 2, 1935 2,117,512 Scott May 17, 1938 2,209,221 C'ain July 23, 1940 2,286,853 Holthouse June 16, 1942 2,301,496 Aldrich Nov. 10, 1942 2,332,149 Horton Oct. 19, 1943 2,364,489 Taylor Dec. 5, 1944 2,451,681 Logan Oct. 19, 1948 

